Epitaxially Grown Metal-Organic Frameworks: Design, Preparation, and Application as Multi-Component Films in Tandem Catalysis

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As exemplified by many catalytic enzyme assemblies in nature, site-isolation is a powerful strategy for performing tandem catalytic reactions to synthesize highly complex molecules.The goals of the project would be to prepare substrate supported, highly oriented MOFs based on the molecular epitaxial approach and then the study of such novel layer-by-layer grown MOFs in tandem catalysis. This approach also would bring a solution to catalysts incompatibility problem. In addition, heterogenizing the catalysts should greatly enhance their stability, even in the absence of an incompatibility. Because MOFs possess tunable structures which are stable and crystalline, we perceived it feasible to integrate multiple functions within one single MOF through a careful design. In this proposal, to achieve sustainable organic synthesis with a high atom and energy efficiency, the development of one-pot cascade processes with no intermediate separation steps using multifunctional catalysts is also highlighted.In this project, we propose to prepare a new class of MOFs providing an exciting platform for deploying two different homogeneous catalysts as building blocks for the next generation of selective and stable heterogeneous catalyst systems. Importantly, the catalytically active moieties in these materials can be made in a site-isolated fashion and the cavities that surround them can be engineered to conceptually to mimic enzymes.Four different classes of novel catalyses are illustrated in the project including: i) metallo- porphyrins/salens catalyzed olefin epoxidation followed by CO2 capture to form cyclic carbonates; ii) metalloporphyrins catalyzed C-H amination via in situ generated nitrenes followed by N-H insertion utilizing carbene equivalents; iii) metalloporphyrins catalyzed insertion of carbenoids into S-H bond followed by photo-induced sulfoxidation of the resulting sulfides and iv) site-isolation of Grubbs second-generation catalysts from the incompatible catalysts (Ir-pincer) which would lead to alkane metathesis.